Interface for digital recorder and display

ABSTRACT

The absence of MPEG processing in a consumer digital recorder player may preclude on-screen message display of recorder status. Various methods are disclosed which facilitate the on-screen display of recorder player status messages. A first embodiment returns a reproduced decoded, analog video signal ( 102 ) to the digital recorder player ( 200 ) for insertion of status messages. In a further embodiment recorder messages data ( 221 ) is coupled to the digital signal decoder ( 100, 117, 520 ) for inclusion with the decoded analog video signal ( 102 ). In a another embodiment a recorder message command (TAG/CMD) is coupled to the decoder ( 100, 510 ) to access recorder specific graphical messages. In yet a further embodiment, recorder message data ( 221 ) is tagged and coupled to the decoder ( 100, 510 ) to select recorder messaged data. In yet another embodiment, digital or analog operating mode determines recorder ( 200 ) message display timing with respect to a reproduced decoded video signal.

This invention relates to the field of digital video recording and inparticular to coupling between various equipment components.

BACKGROUND OF THE INVENTION

A digital video signal may be processed to form a bit stream having areduced bit rate. Such processing for bit rate reduction may beimplemented according to an MPEG compression method, and may beformatted, for example, with an MPEG compatible structure, such as thatemployed in a digital satellite system, for example DSS™ or the proposedGrand Alliance or GA terrestrial system.

A consumer video recorder may be adapted to provide recordingcapabilities for both analog signals and digitally encoded signalsprocessed for example, for compatibility with an MPEG standard andhaving GA or DSS™ signal formats. The adapted consumer video recordermay be considered as two electronic systems within one box, sharing arecording mechanism, servo and control systems. A conventional analogrecording method may be employed where an analog luminance signalcomponent frequency modulates an RF carrier and an analog chrominancesignal component amplitude modulates a second RF carrier. Whenreproduced, the two modulated signals are demodulated, combined andcoupled out for video display.

During both record and replay operating modes, onscreen display messagesmay indicate operational status, warning conditions, tape duration,record time, time code etc., of the video recorder. These on-screendisplay messages or OSDs may be added to the analog video output signalto provide the user with recorder status information.

Digital recording may be achieved by using the consumer video recorderas a digital bit stream recorder/reproducer. The MPEG compatible bitstream, for example transport packets, may be recorded by reformattingthe transport packets to facilitate recording and reproduction. Forexample, the transport packets may be buffered and error detection andcorrection data words computed and added. The bit stream with errorcorrection added may be formatted into recording data blocks or syncblocks containing a predetermined number of bytes which may beaccommodated in each recorded track. The sync block signal may be codedto render the signal more suitable for digital recording, for example,to remove any DC component, or provide spectral shaping of the recordedsignal, such modulation may be produced by “code book” type encoding. Ina playback mode the recording processes are effectively reversed, forexample, the “code book” encoding is decoded, errors are detected andcorrected and the sync block formatting is removed restoring the bitstream to the original MPEG like format.

To minimize the additional cost increment of digital recording andreproduction, MPEG decoding and encoding is not included in therecorder. Thus the recorder must process the MPEG like packet streamwithout changes or additions. Hence the recorder provides a programdelay or time shifting facility. However, recorder status and warningsand tape timer displays, which during analog operation are added to theanalog output signal, may be absent during digital operating modes.Hence, recorder status, etc. may only be ascertained by observation ofthe recorder control panel.

System interconnection and control between a digital signal source,recorder and monitor display may be simplified by the use of abidirectional data bus. However, any interconnection additional to thatof an analog system may present the user with incomprehensibleinstallation complexity and confusion. A simple interconnection methodis required which may provide coupling between a digital signal sourceand display regardless of a recorder's operational status. The simpleinterconnection method must facilitate both analog and digital recorderoperation by utilizing the same interconnection system. In addition,recorder status and warning messages are required for user displayduring both analog and digital recorder operating modes.

SUMMARY OF THE INVENTION

Recorder status, warnings and tape timer displays which, for reasonsdescribed above are absent during digital operating modes areadvantageously provided by the following inventive arrangements. Adigital recording and replay apparatus is adapted for operation with adecoder for digitally compressed video signals. The apparatus comprisesa transducer for reproducing a digital encoded bit stream signal from arecorded medium. Replay electronics are coupled to the transducer forprocessing the digital encoded bit stream signal to produce an outputsignal bit stream for decoding. A status message generator forgenerating a display message is responsive to an operating mode of theapparatus. A receiving means for receives a video signal decoded fromthe output signal bit stream. An adding means is coupled to the statusmessage generator for receiving and adding the display message to thevideo signal.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 depicts in block diagram form packetized signal sources coupledfor decoding and display.

FIG. 2 shows an exemplary block diagram including various inventiveembodiments.

FIG. 3 is an exemplary block diagram showing a simplified switchincluding various inventive embodiments.

DETAILED DESCRIPTION

A simplified consumer digital audio video system is illustrated in FIG.1. Sources of packetized, compressed audio video and control data areshown coupled for decoding and display. A receiver, IRD 100 is depictedcoupled to a receiving antenna 50, however, a modulated signal may beprovided from a cable distribution network (not shown). The modulatedpacketized signal is tuned, demodulated and a user determined program isseparated within the block indicated as PACKET SOURCE 109. An output ofPACKET SOURCE 109 comprises a transport packet stream of audio video andcontrol data which is MPEG decoded to produce audio and video signals byDECODER 117. The output from DECODER 117 is coupled for monitoring bydisplay 300. Other sources of packetized signals are shown coupled witha dotted line as alternative data streams for MPEG decoding by decoder117. Thus DECODER 117 may be utilized to decode transport streams fromexternal packet sources thereby reducing the cost of these othersources. For example, PACKET SOURCE 75 may represent a computer forminga packetized output signal. Such a signal may be derived from a computermemory, or may originate from an external source such as a computernetwork. Such a computer source may reproduce compressed audio video andcontrol data from disk memory. In addition, PACKET SOURCE 75 mayrepresent a digital video disk player such as, for example, a DVD formatdevice. A further source of transport packets may be provided by amagnetic tape player recorder, PACKET SOURCE 200, which may have aformat in accordance with, for example, D-VHS or DVC standards.

A simplified consumer digital video receiver, recorder and displaysystem is illustrated in the exemplary block diagram of FIG. 2. Thesystem employs a digital video signal source, for example an integratedreceiver decoder or IRD 100, an audio video monitor display device 300and a digital video cassette recorder 200, for example employing a D-VHSor DVC format. In the illustrated system, a digital video representativesignal is modulated on an RF carrier and received by an antenna 50.Antenna 50 is coupled to an integrated receiver decoder IRD 100.However, a modulated carrier may be delivered to receiver 100 by a cabledistribution system (not shown). The integrated receiver decoder 100 istuned to the RF carrier frequency and demodulates therefrom an MPEGcompatible transport data stream modulation.

The transport data stream may be decoded to produce analog audio andvideo signals for immediate monitoring by audio video display 300. Thedecoded output signals are represented by signals 101 and 104, which arecoupled between receiver, IRD 100 and display 300. Cost considerationsmay dictate that digital recorder 200 does not include MPEG encoding anddecoding. Hence digital recorder 200 functions as a bit streamrecorder/player, to provide time shifting or program delay capability.The omission of MPEG processing and the degree of complexity required tofacilitate non-standard speed replay capability, precludes imagereproduction in SHUTTLE, SLOW MOTION or TRICK-PLAY modes. Thus insummary, receiver 100 couples an MPEG compatible packet stream todigital A/V bus 112 for recording by recorder 200. Similarly areproduced packet stream from recorder 200 is coupled back to thereceiver for MPEG decoding, and audio/video generation. An additionalconsequence of omitting MPEG processing from the recorder is that statusmessages, in the form of on-screen display messages or OSDs, cannot becombined or added to the replay packetized bit stream. Thus theoperational status of the recorder is not readily obvious to the user.

In addition, since recorder image data is only available during RECORD,PLAY and STOP modes, the user may be uncertain as to the responsivenessof the recorder following control commands. For example, transitioningfrom PLAY to REWIND may result in the replay image switching forexample, to the input bit stream, a condition known as electronics toelectronics or E to E, or for example, the replay image may disappearand be replaced by frozen frame derived by the IRD, or perhaps themoving image may be substituted by a colored field. Thus the user maynot readily associate these visual display effects as indicia ofrecorder mode responsiveness.

The system illustrated in FIG. 2, shows a first inventiveinterconnection arrangement where a demodulated transport bit stream iscoupled from receiver IRD 100 to recorder 200 via a bidirectional databus 112. The transport packet stream is coupled to the data bus via aninterface port 110 and is received at recorder 200 by means of interfaceport 210. The interface ports are controlled via a control data streamwhich is carried on a separate conductor included with data bus 112.Control signals may be derived from user input by activation of controlswitches (not shown), or by user generated IR remote control commands.For example, a user may chose to monitor a digital audio video signalreceived by dish antenna 50. The receiver may be selected by touch orvia a remote control, for example IR. Receiver selection may result inthe automatic monitoring the display selection, i.e. the display isautomatically switched to monitor the MPEG decoded audio video outputs.The user may select a digital RECORD mode which results in coupling thereceived transport stream from IRD 100 via bus 112 to the recorder andinitiating recording. Similarly selection of a digital recorder PLAYmode results in a replayed data stream being coupled via bus 112 fordecoding by decoder 117 of receiver 100.

The MPEG compatible, packetized signal is coupled to recorder 200 andprocessed for recording by block D. REC. 210. A buffer memory isincluded in block D. REC. 210, and buffers the data stream to establisha signal more suited for recording than the packetized signal comprisingbursts of data with variable duration gaps. The buffered data stream isread from the buffer to form record format sync blocks which may beencoded with error detection/correction data words. The sync blockformatted data stream may be modulated for recording as described, andcoupled from recording block D. REC. 210 via a selector switch A4.Selector switches A4 and A5 are controlled responsive to the selectedD-VCR operating mode. For example, in FIG. 2 switches A4 and A5 areshown for digital recording and reproduction, with switch contacts DR,digital record and DP digital playback coupling data streams to and froma rotating head assembly 250. For analog operation, switches A4 and A5assume the alternate position as indicated by AR, analog record and APanalog playback. The sync block formatted data stream from D. REC. 210is coupled to rotating head assembly 250 for recording on a magnetictape.

In a PLAY mode the recorded sync block formatted data stream isreproduced from the magnetic tape by transducing heads 251 positioned onassembly 250. The recovered signal is demodulated by digital replayblock D. Rep. 220, to remove any recording channel modulation. Thereplay signal is then subject to error detection and correction by meansof the data words inserted prior to recording. Following errorcorrection, the sync block formatting is removed and the bit streamrestored to have substantially the same the packet format as thatcoupled to the recorder for recording. The packet stream from block D.Rep. 220 is coupled to interface port 210 which, responsive to therecorder PLAY mode couples the packet stream to the bi-directional databus 112 for MPEG decoding by decoder 117.

Integrated receiver decoder 100 decodes the MPEG compatible packetstream and generates both video and audio output signals. For example,FIG. 2 illustrates video and audio output signals 101 and 102 and acomponent video signal 104, for example S-Video. However, thesedigitally reproduced video signals are without recorder statusinformation usually provided by means of an on-screen display or OSD.

Receiver IRD 100, shown in simplified form in FIG. 2, comprises acontroller, CTRL. 115, which provides overall control of the receiver,for example tuning, packet header control demultiplexing, bus interfacecontrol and selection of packet source for coupling to MPEG decoder 117.In addition the receiver status, or operational mode, may be indicatedby means of an on-screen display message added to the decoded videosignals. Controller 115 may construct an on-screen display message ormay read a predetermined stored message from memory block MEM. 510. Theon-screen display message or OSD is coupled to an OSD inserter or adder,block 520 where the message is formatted for analog video display andadded or combined with the MPEG decoded video signal. The video with OSDsignal is coupled out via output amplifier 118 for display by monitordisplay 300.

In FIG. 2 recorder player 200 includes an on-screen display generator,OSD. GEN. 270, coupled to a control system CTRL 205. In response tosignals from the recorder control system 205, OSD generator 270generates status or warning messages appropriate to the operationcondition. These messages are formatted as video signals for insertionor inclusion with an analog video signal in block, OSD. ADD 275. Analogvideo signals are coupled to the on-screen display adder 275 from avideo selector block SEL. 280.

Selector 280 is controlled by control system 205 and provides selectioncapability between various analog signal sources. For example, switch A1provides analog input signal selection between a tuner derived signal, abaseband analog signal input and an MPEG decoded audio video outputsignal 102. The output from switch A1 is coupled for analog recording byblock A. REC.

Selector switch A3 of SEL 280 advantageously provides selection ofsignal coupling to on-screen display adder 275. In FIG. 2 switch A3 isshown providing an inventive coupling of the video component of outputsignal 102 to the input of on-screen display adder 275. Thus, recorderplayer 200 status messages generated, for example during playback, maybe added to video signal component 102 decoded from the output transportpacket stream. Thus the digitally derived MPEG decoded replay signalwith on-screen messages added, signal 103, may be viewed by display 300.

During analog operation of recorder player 200, switch A3 couples ananalog replay signal, shown as signal VHS, to on-screen display adder275. Thus during analog operation OSD messages are added to the analogreplay video signal. When digital recording is selected, OSD messagesmay be advantageously added to the analog video signal 102 decoded fromthe reproduced bit stream. Thus, by means of this advantageous feedbackconnection recorder status messages are combined with the videocomponent and output as analog signal 103.

Switch A2 of selector SEL. 280 advantageously provides a connectionwhich bypasses on-screen display adder 275 and allows output signal 102to be coupled directly to monitor display 300. Thus the bypass action ofswitch A2 allows viewing of decoded output signals and removes thepossibility of signal degradation due to adder 275. The bypass path A2may be automatically selected when the recorder is OFF, in a STAND BYmode, or when viewing a decoded, non-recorded “live” bit stream. Topermit viewing of decoded non-recorded signals during analog recording,the bypass switch may be manually activated. The advantageous bypassconnection obviates unnecessary analog recorder signal processing, forexample via the E/E recorder path which inherently degrades thedigitally derived signal 102. In addition the advantageous bypassfunction may be facilitated, for example by mechanical contact, suchthat switch A2 allows receiver IRD 100 to be connected to monitordisplay 300 without regard to the operational status of recorder 200.

On-screen display generator 270 generates messages formatted withspecific horizontal and vertical synchronizing timing such that wheninserted into the video signal the message is displayed at apredetermined position on the display screen. However, when operating inthe digital replay mode and employing the advantageous feedbackconnection discussed above, OSD messages may be advantageously generatedwith horizontal and vertical synchronizing timing which is differentfrom that employed during analog recorder operation. This differenthorizontal and vertical synchronizing timing advantageously compensatesfor replay signal propagation and MPEG decoding delays encountered, forexample, in receiver 100. Thus, the use of different OSD synchronizingtiming advantageously achieves substantially the same predeterminedmessage position in either analog or digital recorder operation.

Processing and MPEG decoding time delays may amount to periods ofmultiple frames. A multiple frame delay, or temporal offset, will resultin an OSD message preceding an actual reproduced visual event. Thistemporal offset, where the recorder OSD message precedes a reproducedevent, may be revealed as a consequence of a user control command andthe delayed appearance of the corresponding reproduced image effect. Thetemporal offset may represent a more significant problem when displayinga recorded time code signal or the recorder tape timer. For example,during tape replay specific events may be noted from an on-screendisplay of the recorder tape timer or an OSD of a recorded time codesignal. The noted times allow for subsequent location of the selectedevents. However, should the noted times be used as edit points forelectronic editing performed between recorders, the resultant editedscenes will precede those selected during previewing. The effect of thetemporal offset between the message and the replay image may beadvantageously eliminated by a delaying, message generation, messagecommunication, OSD presentation or by modifying the tape timer/time codenumbers or count. In recorder 200 a delay, depicted as DLY. 207, may beselected by switches A7 or A8. For example, when decoded video signal102 is fed back for recorder OSD message insertion at block 275, an OSDmessage command may be generated responsive to controller 205. Themessage command signal CMD, from controller 205 is illustrated coupledto switch A7 and delay DLY 207. Switch A7 is controlled responsive tothe recording mode selected for recorder 200, i.e. analog or digital.Switch A7 is shown in the digital mode, and selects a delayed version ofsignal CMD from delay 207. The delayed command signal results in thegeneration and insertion of an OSD message which is substantiallycoincident with decoded video signal. An alternative arrangement employsswitch A8 which may insert delay 207 into the output from the OSDgenerator 270. In this arrangement switch A7 is connected to the outputof controller 205. Switch A8 may also be employed to delay coupling ofsignal CMD to bus 112 and IRD 100. The temporal offset between the OSDmessage and the decoded replay image may also be corrected in receiver100 by the introduction of a delay, for example as depicted by DLY. 116,into either the memory accessing signal or the memory output signal.Synchronization of repay image and OSD may be achieved by variousmethods, for example, by means of a delay using a clocked data latch,shift register, monostable multivibrator, etc. A tape timer or time codeOSD may be synchronized with the decoded image, for example during editmode preview by arithmetic manipulation of the display numerals. Thusthe selected image and associated display numerals may be entered toenable an electronic edit to be performed. During analog operation ofrecorder 200 the command signal CMD, from controller 205 is not delayedand switch A7 couples directly to generator 270.

In another inventive embodiment, on-screen display messages originatedby recorder 200, may advantageously utilize the on-screen displaycapability of receiver 100. Recorder derived messages may be coupled viathe control conductor of data bus 112 to receiver 100 for on-screendisplay insertion at block OSD 520 of FIG. 2. The recorder message datamay be formatted as a text message by generator 270, to which a tag orlabel is appended. The tagged text message shown as signal 271, iscoupled to controller 115 of IRD 100 for separation from other controlbus data. Following separation the text message is coupled for displayformatting and video insertion by OSD 520. The text message is generatedresponsive to OSD command signal CMD from controller 205. As describedearlier, signal CMD may be subject to delay at block 207. However, thetext message from block 270 may be delayed at an alternative point byswitch A7 insertion of delay 207.

In a further inventive embodiment, receiver 100 includes a memory 510which contains receiver on-screen display messages and OSD messagesspecific to recorder 200. Recorder specific messages may be accessedresponsive to recorder on-screen display command signal, CMD, which maybe coupled via the control bus to controller 115. In recorder 200 theon-screen display command signal CMD, is generated by controller 205which in addition determines the message to be generated. Thus commandsignal CMD, may be advantageously coupled to receiver 100 to enableaccessing and display formatting of recorder specific graphical messagesstored in a memory 510.

In yet another inventive arrangement receiver 100 may adaptively selectbetween the recorder text message or a receiver graphical messageresponsive to a recorder command. The selection between the recordertext or IRD graphical message display permits the interconnection ofrecorders and receivers of differing ages having different features andfacilities. For example, an older receiver may be connected to arecently manufactured recorder thus, the receiver memory may not containpreprogrammed graphical messages to support recorder on-screen messagepresentation. Thus the receiver may display the simple text messagegenerated by the recorder. Conversely, a more modern receiver may bepreprogrammed with selections of graphical messages for a variety ofproducts of various manufactured ages and these various graphicalmessages may be displayed in place of the recorder text message.Selection between simple text or graphical message is facilitated by thetag or label which is appended to the text message. For example, the tagor label may contain the command signal CMD which selects, and enablesthe required recorder specific message. In addition the label mayprovide sufficient data capacity to communicate recorder profileinformation relating to, for example, the date of recorder manufacture,model, version or revision level and serial number. When the textmessage with tag or label is received by controller 115, the tag orlabel is interpreted which results in the selection of a recorderspecific graphical message from IRD memory 510. However, if the receivermemory is not preprogrammed with the specified recorder message or witha message specific to the recorder profile, the tag enables formattingand display of the appended simple text message. As described previouslya delay element may be inserted to compensate for temporal and spatialdisplacement between the OSD message, text or graphical, and thereplayed decoded image.

FIG. 2 illustrates a monitor display 300 having three analog signalinputs; audio video signals 101 and 103, and an audio and componentvideo signal 104, for example, S-video or luminance and coloringcomponents Y, Pr, Pb. In addition, display 300 may receive audio andvideo signals via radio frequency signals, depicted as RF IN. A signalselector 310, couples as is known, to video and synchronizing processingcircuitry, not shown, which in combination generate an image display.Signal selector 310, may be controlled by user activated switcheslocated on display 300, or by user initiated remote control commandstransmitted via a modulated IR control stream. The three baseband inputsignal illustrated may be advantageously selected by automated controlof selector switch 310. For example, selection of digital recording orreplay modes may automatically select an input signal containingrecorder OSD status display information. The recorder status OSD may begenerated and originate as previously described. In addition, theprovision of multiple baseband signal inputs may allow function specificdevice interconnection. For example, the direct viewing of a decoded,non-recorded, signal from IRD 100 may be facilitated by use of, forexample, output signal 101, or component video signal 103, with IRDoutput signal 102 routed for recorder OSD insertion to form A/V signal103.

FIG. 3 illustrates the use of a reduced cost display, for example, asdepicted as display 301. To reduce the display cost the number of signalinputs may be limited to, for example, an RF input, a component video orS-video input and one audio video signal input. The advantageousselection and bypass capability of selector 280 of FIG. 2, permitsdisplay 301 to monitor recorded, and non-recorded material via a singleA/V input. However, the display may advantageously utilize the componentvideo signal connection to determine and control the display inputselection in addition to signal coupling. For example, since componentvideo signals or S-VIDEO signals may be assumed to provide superiordisplay image quality to that attainable from an NTSC encoded signal,the presence of such component signals coupled to a component signalinput may automatically cause selection of the component signal source.Thus when both component and composite signals are coupled to display301 inputs 1 and 2 respectively, the input controller has logic whichpredetermines selection of the component signal as a preferred input.However, this automated input selection may prevent monitoring ofsignals containing recorder specific on-screen display informationcoupled from recorder 200 of FIG. 2. However, the automated,preferential input selection may be advantageously utilized to enableremotely controlled selection of the audio video signal, for examplesignal 103 at input 2. Signals containing on-screen display informationcoupled via recorder 200 may be viewed on display 301 by an inventivecontrol of component signal 104 by means of allowing or terminatingoutput coupling signal 104 from IRD 100. For example, user selection ofa non-recorded bit stream, i.e. received signal, will result incontroller 115 of receiver 100 enabling generation or outputting ofcomponent signal 104, having for example, an S-VIDEO format. Theselection of a recorded image signal for display will result incontroller 115 terminating generation, or outputting of component signal104. Thus controller 312 of monitor 301 is coupled to the componentsignal input terminal to senses via signal 309 the absence of signal 104and causes input selector 311 to switch from the component input signal104, on input 1 to, for example, audio video signal 103, on input 2coupled via selector 280 of recorder 200 in FIG. 2.

What is claimed is:
 1. A digital recording and replay apparatus adaptedfor operation with a decoder for digitally compressed video signals,said apparatus comprising: a transducer for reproducing a digitalencoded bitstream signal from a recorded medium; replay electronicscoupled to said transducer for processing said digital encoded bitstreamsignal to produce an output signal bitstream for decoding; a statusmessage generator for generating a display message responsive to anoperating mode of said apparatus; means for receiving a video signaldecoded from said output signal bitstream; and, adding means coupled tosaid receiving means for adding said display message to said videosignal decoded from said output signal bitstream.
 2. The digitalrecording and replay apparatus (200) of claim 1, wherein said receivingmeans (280)has a first mode of operation wherein said video signal (102)is coupled for display message addition, and a second mode of operationwherein said video signal (102) bypasses said display message addition.3. The digital recording and replay apparatus (200) of claim 2, whereinsaid first mode of operation is selected during powered operation ofsaid apparatus (200) and said second mode of operation is selected whensaid apparatus (200) is not powered.
 4. The digital recording and replayapparatus (200) of claim 2, further comprising means (A2) for selectingsaid first and second modes of operation of said receiving means.